The invention proceeds from a procedure to operate a metering device of an exhaust gas emission control system and from a device to implement the procedure according to the class of the independent claims.
The subject matter of the invention at hand is also a computer program as well as a computer program product.
In the German patent DE 100 56 016 A1, a procedure is described, in which a regeneration is introduced as a function of a parameter of a particle filter disposed in the exhaust gas area of an internal combustion engine. The particle filter is a component of the exhaust gas emission control system. The temperature of the particle filter during the regeneration depends on the one hand on the condition of the particle filter and on the other hand on the operating condition of the internal combustion engine. The increase of temperature of the exhaust gas is, for example, implemented by the introduction of non-combusted fuel into the exhaust gas area of the internal combustion engine, which reacts exothermally on a catalytically active surface with the residual oxygen contained in the exhaust gas. The heated exhaust gases heat up the catalytically active surface as well as especially the components of the exhaust gas emission control system, which are disposed downstream behind the catalytically active surface.
In the German patent DE 101 59 849 A1, a procedure and device are described, in which a reagent substance under pressure is sprayed into the exhaust gas of an internal combustion engine in front of the SCR catalytic converter. Provision is made for fuel to be to reagent substance, which acts especially as a reducing agent for the NO2 proportion of the exhaust gas.
In the German patent DE 10 20 04 061 247 A1 (unpublished), a procedure and device are described, in which a reagent substance under pressure is sprayed into the exhaust gas of an internal combustion engine in front of an exhaust gas emission control system. Provision is also made in this case for fuel to be the reagent substance, which reacts exothermally on a catalytically active surface with the residual oxygen present in the exhaust gas. The heated exhaust gas stream heats the components disposed downstream behind the catalytically active surface. The metering device for the reagent substance contains a switchable safety relief valve, a continuous metering valve and a reagent substance introduction valve designed as a check valve. The reagent substance introduction valve sprays the fuel into the exhaust gas area. Provision is made for a pressure sensor, which acquires the pressure of the reagent substance in the metering device.
In exhaust gas emission control systems of this kind, significant importance is attributed to the correct manner of operation of the metering device. In the case of an underdose of the reagent substance, the danger exists that a reagent substance slippage occurs and/or that a catalytic converter/particle filter is damaged. Provided that provision is made for fuel to be the reagent substance; in the case of an overdose of fuel, which is supposed to react exothermally with oxygen in the exhaust gas area, a very quick increase to an inadmissibly high temperature must be anticipated, by which exhaust gas components as well as the exhaust gas emission control system can be damaged. Should the situation of inadmissibly high temperatures arise, a significant fire danger can arise in the worst case scenario.